Conventional scanning system can be approximately divided into two segments that are handy scanning system and flat-bed scanning system. A conventional scanning system apparatus includes a light source, a mirror, and a lens set, which are used to guide the reflecting light to a charge couple device (CCD). The charge couple device is utilized to generate an image signal. A pre-processing element is used to respone an image signal and adjust dc gain of the image signal. An analogue to digital converter is used to convert adjusted image signal to a digital signal and a post-processing element to generate an image code by processing said digital signal through highlight, shadow, and Gamma correction. In practicing the scanning system, the light source is reflected from the surface of a document, then it is reflected against from the mirror and focused by a lens set. The mirror and the lens set are used to guide the light beam to a CCD.
Subsequently, the light beam is converted to an image signal by the CCD, and direct current (d.c.) gain of the image signal is adjusted by a pre-processing element, i.e. a d.c. gain voltage amplifier. Then the adjusted image is fed to an analogue to digital converter (ADC) for converting adjusted image signal to a digital signal. The digital signal is fed to a post-processing element to generate an image code by processing the digital signal through highlight, shading correction, and Gamma correction.
However, in conventional scanning apparatus, the document is fed into the scanning apparatus by using rollers, which will cause damage of the document. Therefore, the output quality of the scanning system can not meet the requirement of the present demand. Further, the cost of the conventional scanning apparatus that is built in a computer is high and the structure of the apparatus is also complicated.